Drop "-euler" from virtual sensor types

As discussed in
https://github.com/w3c/deviceorientation/pull/124/files/738168e2d57e24e5094517700ab7d2b08ca2bfe4#r1414556615
we should use the same virtual sensor types for the device orientation part
of this spec as well as the Orientation Sensor spec, just like the same
virtual sensor types are used for device motion and the Generic Sensor
API-based specs like Accelerometer and Gyroscope.

Compared to device motion, however, we have an additional problem in that
device orientation data is provided in Euler angles and Orientation Sensor
uses quaternions.

The idea is to parse readings by reading alpha/beta/gamma keys from the
WebDriver extension command and use them in the "fire orientation event"
algorithm and skip using quaternions altogether. The Orientation Sensor spec
can then augment the "parse orientation data reading" algorithm with the
required steps to both 1) accept a "quaternion" key in the WebDriver
extension command (and convert it to Euler angles as well) and 2) derive a
quaternion from the alpha/beta/gamma Euler angles.

index.bs

@@ -671,7 +671,7 @@ Therefore, instead of requiring implementations (and automation users) to provid
 <h4 id="parse-orientation-data-reading-algorithm">Parse orientation data reading algorithm</h4>
 
 <div algorithm>
-To perform the <dfn>parse orientation data reading</dfn> algorithm, given a JSON {{Object}} <var>parameters</var>:
+To perform the <dfn export>parse orientation data reading</dfn> algorithm, given a JSON {{Object}} <var>parameters</var>:
 
     1. Let <var>alpha</var> be the result of invoking <a>get a property</a> from <var>parameters</var> with "<code>alpha</code>".
     1. If <var>alpha</var> is not a {{Number}}, or its value is <strong>NaN</strong>, +∞, or −∞, return <strong>undefined</strong>.
@@ -692,21 +692,21 @@ Note: <var>reading</var> is defined as a <a>map</a> in the algorithm above to pr
 
 </div>
 
-<h4 id="absolute-orientation-euler">The "absolute-orientation-euler" virtual sensor type</h4>
+<h4 id="absolute-orientation-virtuals-sensor">The "absolute-orientation" virtual sensor type</h4>
 
 The <a>per-type virtual sensor metadata</a> <a>map</a> must have the following <a for=map>entry</a>:
 :
 : <a for=map>key</a>
-:: "<code>absolute-orientation-euler</code>"
+:: "<code><dfn export data-lt="absolute-orientation virtual sensor type">absolute-orientation</dfn></code>"
 : <a for=map>value</a>
 :: A <a>virtual sensor metadata</a> whose <a>reading parsing algorithm</a> is <a>parse orientation data reading</a>.
 
-<h4 id="relative-orientation-euler">The "relative-orientation-euler" virtual sensor type</h4>
+<h4 id="relative-orientation-virtual-sensor">The "relative-orientation" virtual sensor type</h4>
 
 The <a>per-type virtual sensor metadata</a> <a>map</a> must have the following <a for=map>entry</a>:
 :
 : <a for=map>key</a>
-:: "<code>relative-orientation-euler</code>"
+:: "<code><dfn export data-lt="relative-orientation virtual sensor type">relative-orientation</dfn></code>"
 : <a for=map>value</a>
 :: A <a>virtual sensor metadata</a> whose <a>reading parsing algorithm</a> is <a>parse orientation data reading</a>.